DC-to-DC converters for stepping up a DC voltage value are well known in the art. One type of DC-to-DC converter uses an inductive "fly-back" principle to provide an increased voltage value. An inductive "fly-back" converter includes an inductor having a first terminal connected to a DC voltage source and a second terminal connected to a switching circuit. A drive circuit periodically energizes and de-energizes the switching circuit to connect and disconnect the second inductor terminal with electrical ground and thereby energize and de-energize the inductor. When the inductor is energized, a magnetic field is established by electrical current flowing through the inductor. When the electrical current through the inductor is abruptly cut off, i.e., the inductor is de-energized, the magnetic field collapses. When the magnetic field collapses, a voltage is developed across the inductor. This developed voltage is added to the value of the DC voltage source thereby resulting in voltage spikes at the second terminal of the inductor. These voltage spikes have a value greater than the value of the DC voltage source. A rectifying diode and filter capacitor is connected to the second terminal of the inductor and provides a DC voltage having a value greater than the value of the DC voltage source.
The use of DC-to-DC converters in the automotive art is also known. One particular use of DC-to-DC converters in the automotive art is in the area of electric assist steering. U.S. Pat. No. 4,660,671 to Behr et al., assigned to the assignee of the present application, discloses a power assist steering system that includes an electric assist motor, a drive circuit, a main power connection relay electrically connected between the vehicle battery and the drive circuit, and a DC-to-DC voltage-up converter connected to the drive circuit. The DC-to-DC converter provides a DC voltage having a value greater than the value of the battery voltage. The increased voltage value is necessary for proper operation of the drive circuit. The DC-to-DC converter disclosed in the '671 patent is a commercially available item. Such a converter uses an externally connected inductor coil. While commercially available DC-to-DC converters have proven to be quite satisfactory in their function, it is desirable (i) to reduce the number of electrical components in an electrical system, (ii) to reduce the physical size of the system, and (iii) to reduce the cost of manufacturing the system.